The three screws will allow you to carefully pry the lens out of the housing. You will find your basic automotive 12vdc socket holding a series 1141 bulb behind it. Hopefully, a new bulb is all you need and you can find them cheap at the auto parts store (or, you can get fancy and go LED.
Personally, I did not seal the lens to the housing when I installed the lamp last time. So far, no water intrusion.
Sorta new (usually dirty) Nissan Titan XD (hardly paid for)
Middle-aged Safari SE
Young, lovely bride